Continuously playing phonograph



2 SHEETS-SHEET 1 C. M. SINNETT ETAL Nov. l1, 1952 CoNTINuoUsLY PLAYING PHONOGRAPH Filed April 29, 1950 gf Wifi/.551 Hg Arro'e/s/EY Nov. 1l, 1952 c. M. slNNETT ETAL CONTINUOUSLY PLAYING PHoNoGRAPH 2 SHEETS--SHEET 2 Filed April 29, 195o Patented Nov. 11, 1 952 UNITED STATES PATENT ori-fics# CONTINUOUSLY PLAYING PHONOGRAPI-f` Chester M. Sinnett, Westmont, .and 4=IIerbert Belair, A Palmyra, N. J., assignors to Radio Corporation oir' America, a corporation of Delaware Application April 29, 1950, Serial No. '159,106

8 Claims. 1

This invention relates to continuously playing phonographs and has for its principal object the provision of an improved apparatus and method of operation whereby lone phonographis put out of operation and another phonograph is put into operation automatically and Without appreciable time delay between the sound records reproduced by the two phonograph's.

In achieving this result, use is made of index- '10 by which they are operated. v'lhe'appa-ratus is` preconditioned for the startinglof sound repro duction by pressing of startingbutton switches each of which lfunctions vto energize the powers control relay 'of a diferentphonograph so that the turntables of both phonographs` are rotated until the indexing signals are reproduced'from the records, thereby deenergizing the power relays and opening the circuits of the turntable motors. Startingof sound .reproduction from either record is initiated by pressing of the correspondingA starting button and, if the phonographs are of the automatic .recordchanging type, the reprohr ductionof sound from the records continues in-` definitely.` Y

Thus,..if the record on the No. l phonograph is liirst, played, the fade signal at theend of its sound 'record'functions to energize theNo. 1 'fade relay which (l) closes the No. 2 power relay circuit, thereby starting the No. 2 phonograph., and (2) (at the .same time.) completes the circuit of a time delay 4relay by which. the amplifier and loudspeaker are later disconnected `from the No. 1 phonograph and connected to the No. 2 phonograph... This .time delay `relay is providedwith a contact whichcompletes a holding circuit for itself through contacts which are engaged only when the No. 2-fade relay isnot energizedby a fade signal from a record on the No.v 2 phonograph.

When the No.2 phonograph has .finished play-l ings 'its record, the No'. 2 fade relay is energized. thereby '(1) completing a circuit through which` the No. 1 power relay is 4energized. and the No. 1 phonograph is started, and (2') opening the holding circuit of the time delay `relay fandiaiterf switching the' amplifier `and loudspeakcrtothe No. l phonograph.

In order that this cycle of operation 'be-continuous without an appreciable pause'orovere lap for an indeiinite period, fit-is only necessary l' that the Vindexing signal and fade signal be prop-- erly positioned. l Also, -therema'y be-associatelif with the loudspeaker a switch by'which itis temporarily short circuited as the amplier is L switched from one phonographto another.

Importantobj ec-ts of 'the invention are the pro-f'- vision of an improved sound reproduction apparatus whereby sound may loel continuously reproducedirom successive records without apparent" interruption, and the provision'of 'improvedimeans for fading reproduced sound from 4one fphono graph to another.

The invention will be better understoodfirom^ the following description considered in Vconnect-"- tion with the accompanying drawings vin which Figure '1 is ascheinatic circuit or wiring-diagram of one form of improved sound reproduce ing apparatus according to our present invention; z

and

Figure 2 is a graph 'showing the cycleof operation of our improved'sound reproducing sys-'- tem in point -of time.`

Referring, lirst, to Figurewlfthe apparatus in` cludes No. 1 and No.2 phonographs each'of which* is diagrammat-ically shown as kincluding apickup i head I, a turntable -2 for supporting one or more records 3, Va turntable drive `motor 4 anda brake 5 for cooperating witht-he turntable." The brake e 5 is designed to beset when themotoris noten-- ergized and 'released` when powerL vis furnished" to Vthe motor.

up head and, in Vits lowerl'clo'sed position, Lcon-- nects the amplifierV l0 totheNo2 pickup head.

The switch 12 isk biased-toits upper -clo'sedu'po-fsition 'and is moved .from `this position toits .low-l er closed: positiono'nly .inresponseto excitationof. J Excitation .of the:

a time ldelay .relay coil! t3. coil 113 falso functions. to complete, through 'con-VV tacts I4, a holding..circuit'forsthecoil andtail briey short circuit `the loudspeaker il through:v

the contacts l I 5.

The No. v1 phonograph is providedwitha power supply `control relay I `6 vhaving .a switch ielement; `Il which controls the supply :of :current to therlo..-r l

1 turntable motor and a switch element I8 which controls a holding circuit for the relay coil.

Connected yto the No. l pickup head are an indexing relay I9 and a fade relay 20. The indexing relay I9 has a switch blade 2| which (1) cooperates with the switch blade I8 to complete the holding circuit of the power supply relay I when the indexing relay I9 is not energized by an indexing signal, and (2) serves to interrupt this holding circuit and stop the No. 1 motor when the indexing relay is energized. The No. l motor is always started in response to closure of a start switch 22 either manually or in response `to a member 23 forming a, part of the record change mechanism.

The fade relay 20 has one switch blade 24 which completes the circuit of the time delay relay coil I 3 in response to a fade signal reproduced before the end of the sound record on the No. 1 turntable. The fade relay 29 also has another switch blade 25 which completes a circuit for the No. 2 power supply relay 2B for starting the No. 2 motor. K

Suitable lter units 21 and 28 may be interposed in the circuits of the No. 1 indexing and fade relays for selectively transmitting the indexing and fade signals to these relays. This selectivity may be based on a difference in frequency or on other distinguishable characteristics.

The No. 2 power supply relay 26 is similar in all respects to the No. 1 relay I6. The No. 2 indexing relay 29 and filter unit 30 are likewise similar to the No. 1 relay I9 and lter 21. The N0. 2 fade relayilter 3l is similar to the No. 1 filter 28 but certain dierences of the No. 2 fade relay 32 should be noted. It will be observed that the relay 32 has one switch blade 33 which, together with the switch I4 of the time delay relay, completes a holding circuit of the time delay relay when the fade relay 32 is not energized. The No. 2 fade relay also has another switch blade 31% which completes a circuit for energizing the No. 1 power supply relay I6 when the No. 2 fade relay 32 is energized, at which time the holding circuit ofthe relay I3 is broken at the switch 33, thereby allowing- (1) the switch blade I2 to move to its upper closed position, (2) the switch I4 to open, and` (3) the loudspeaker II to be temporarily short circuited.Y The effect of this sequence of switching operations is to transfer sound reproduction from the No. 2 to the No. 1 unit.

.The No. 2v start button 35 is similar to the No. 1 startbutton 22 with the exception that it includes; a third contact 35 through which the relay I 3 is operated to connect the amplier I0 to the No. 2 phonograph and to complete its holding-circuit whenever sound reproduction from the No. 2'unit is to follow. The start button 35 may be operated manually or byr a member 31 whichforms part of the record changing mechanism of the No. 2 phonograph.

Operation of the apparatus is initiated by closing the start button switches 22 and 35 either manually, or automatically in response to operation of the automatic record changer mechanism. In either case, the control is such that the records arev rotated untilthe indexing signal is received by the relay I9 or 29 at which point the phonographs stop and remain stationary until their startxbutton switches are temporarily closed again.

Assuming `that both phonographs have been brought to restin response to an indexing signal and that the No. 1- unit is to be operated rst, the

start button 22 is closed temporarily and the record is played until the fade signal section of the record is reached. When the fade signal is received by the relay 20, the switches 2d and 25 are closed. Closing of the switch 2l! energizes the relay I3 so that the amplier connections are switched from the No. l to the No. 2 unit. Closing of the switch 25 energizes the No. 2 power supply relay 25 thereby transferring sound reproduction to the No. 2 unit. The No. 2 record is played until its fade signal is received by the No. 2 fade relay 32. When this occurs, the switch 33 is opened, thus breaking the holding circuit of the relay I3, and the switch 34 is closed so as to energize the No. 1 power supply relay I6. This completes the cycle of operation.

As indicated above, the incoming record is always at the correct starting point when sound reproduction is transferred to it because of the proper choice of the positions of the indexing and fade signals thereon. The position of the indexing signal is ahead of the beginning of the recording. The angular distance between them is equal to or greater than that required to bring the turntable to a stop plus the time required to and the end of the recording. The fade signal should be ahead of the end of the recording so the same time will elapse between the fade signal and the end of recording as was allowed to bring the record up to speed and to the start of recording. The requirement for equivalence of time is to be emphasized because the distances 'are not necessarily the same. The time delay relay must, of course, also be timed to the same time interval.

For example, if (l) a 45 R. P. M. record player can be stopped by means of the indexing signal in 1/3 second from the time the signal is applied and the record turns 1/8 revolution during this period, and if (2) it takes l@ second to bring the record up to speed from the time the fade signal is applied and during this period the record turns 0.2 revolution, then the total time required to stop and start the record would be 1/s-I-1/225/e second, and the total angular distance would be 1/8 +0.2:0.325 revolution The angular distance between the indexing signal and the start of the music can therefore be set to 0.325 revolution. With this choice of the indexing signal position, the record would turn at normal speed until the indexing signal is reproduced 0.325 revolution ahead of the beginning of music or other recording. It would then be braked to a stop with l/8 of a revolutionand come to rest with the pickup reproducing stylus 0.2 revolution ahead of the recording. Since, as was assumed for this particular example, the record requires 0.2 revolution and 1/2 second to come up to speed, the fade signal will have to be located 1/g second before the end ofthe recording and the time delay relay set to 1/2 second. During this period, the record travels at a constant speed of 45 R. P. M., so in 1/2 second it will travel revolution. Therefore, the fade signal will have toV be placed revolution ahead of the end of recording.

The calculation of the required position` for the indexing and fade signals vfor any other turntable constants follow the same method illustrated by the above example. In all cases, the timing is so chosen so that the incoming record output is connected to the amplier just as the recording begins andthe outgoingrecord is'. dis;- l

connected just as the recording ends.. The time interval. between reproduction of both records is' very `brief'and of the order of T16 second `or less,.

the interveningvsil'ent period -being provided by the` loudspeaker short circulating switch I5. With this arrangement, practically inaudible change-over between records can be provided.y

Another way of showing the operation of the invention is by the graph of Figure 2.` The opera.'-V

tion ofthe record changer is shown againstrtime, the-ordinate being the distance expressed in angular measure. At point A, both turntables are started by pressing the respective starting buttons 22 and 35. At point' B, both phonographs will produce the indexing signal, both motorsV become deenergizedand brakes set. At point C, the turntables are at rest. The horizontal distance BC 'corresponds to 'the time required to bring the turntable to a stop, and the vertical distance BC represents the angular distance required to bring the turntable to a stop. From C toxD, both turntables are waiting. At point D, turntable No. 1 has been started by pressing its starting button 22. During the time interval which is' shown by the horizontal distance D and E, the turntable is accelerated. The distance through which it travelsis expressed by the `vertical distance from D to E. At point E, the 'recording starts and the first" record continues to play. Eventually, this record reaches point F, at which an inaudible signai is reproduced causing the turntable of No. 2 phonograph to start accelerating at point I until it reaches normal speed at point J. The first record continues playing from F to G, and at point Gr the time delay relay operates and fades from the rst to the second record. Turntable No. 1 continues rotating to point H at which time the terminal groove of the rst record trips the mechanism to effect changing of records on No. 1 phonograph between points N and O. Turntable No. 1 continues to rotate from point O to point P at which time the indexing signal on the new record of No. 1V

phonograph has come under the needle. This corresponds to the point B and is the point at which the brake of No. 1 phonograph is now applied to cause its turntable to stop at point Q. The No. l turntable then remains stationary until the point R, which corresponds to the point D, is reached. Meanwhile, from the point J on, the second record plays on turntable No. 2 and, at the point K, the above described cycle is repeated to effect transfer of playing to the No. l phonograph again for playing the third record, stopping of the No. 2 turntable with a new record thereon, and so on through the points S, T, U, etc.

What is claimed is:

1. The combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from a record sound groove preceded by an indexing signal record groove and followed by a fade signal record groove, separate drive means for rotating said turntables, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, and fade signal responsive means for subsequently transferring sound reproduction from one to another of said sound reproducing devices upon further rotation of said turntables.

2. The combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from arecord sound groove preceded vby lan indexing signal recordv groove and followed. by'` a fad'eLsig-x nal record groove, separate drive means for ro-ftating saidv turntables, an audio frequency; am-

plier, indexing signal responsive m'eanssforv individually stopping rotation of said fturntablesr precedent to said sound reproduction, Vand fade;

signal responsive means for subsequently switchf;

ing said amplier from one of said pickup de.-

vices to the other following said sound .repro-x duction from said one of the pickup devices.,

3. The combination of a pair of soundrecordreproducing devices each including a turntable..- and a pickup device for reproducing sound from z a vrecord vsound groove preceded by an indexingM signal record' groove and followed by afad'e. sig-inal record groove, separate drive means forro-.

tating said turntables, an, audio frequencyam:

plier, indexing signal responsive means for in;- Y dividually stopping rotation of said turntables:

precedent to said sound reproduction, means for selectively restarting one of said. turntablesand: x

means responsive to a fadeA signal reproduced by one of said sound reproducing devices or'subsequently startingrotation oflthe turntable.A of

the other of said sound reproducing devicescwith predetermined time delay.

4. The combination of a pair of sound recordn reproducing `devices each including a turntable. and a pickup device for reproducingsound from a record sound groove preceded by an indexing signal record groove and followed by a fade signal record groove, separate drive means for rotating said turntables, an audio frequency amplier, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, and fade signal responsive means including a time delay relay for subsequently switching said amplifier from one to another oi said sound reproducing devices upon further rotation of said turntables.

5. lThe combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from a record sound groove preceded by an indexing signal record groove and followed by a fade signal record groove, separate drive means for rotating said turntables, an audio frequency amplifier, a loudspeaker connected to the output of said amplifier, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, and fade signal responsive means for subsequently simultaneously short circuiting said loudspeaker and switching said amplifier from one to another of said pickup devices upon further rotation of said turntables.

6. The combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from a record sound groove preceded by an indexing signal record groove and followed by a fade signal record groove, separate drive means for ro-.

tating said turntables, an audio frequency ampliiier, a loudspeaker connected to the output of said amplier, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, fade signal responsive means including a time delay relay for subsequently switching said ampliiier from one to another of said pickup devices, and

means completing a holding circuit for said relay only when said amplifier is switched in one predetermined direction between said pickup devlees.

'7. 'The combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from a record sound groove preceded by an indexing signal record groove and followed by a fade signal record groove, separate drive means for rotating said turntables, an audio frequency amplier, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, means for selectively restarting one of said turntables, means responsive to a fade signal reproduced by one of said sound reproducing devices for subsequently starting rotation of the turntable of the other of said sound reproducing devices and for switching said amplier from one of said pickup devices to the other with predetermined time delay, and automatic trip means for restoppng said one of said turntables following said switching.

8. The combination of a pair of sound record reproducing devices each including a turntable and a pickup device for reproducing sound from a record sound groove by an indexing signal record groove and followed by a fade signal record groove, separate drive means for rotating said turntables, indexing signal responsive means for individually stopping rotation of said turntables precedent to said sound reproduction, means for selectively restarting each of said turntables, au-

tomatic trip means for individually restopping said turntables, a sound amplifier selectively connectable to one or the other of said pickup devices, a loudspeaker device connected to said 4amplifier for reproducing amplied sound from said pickup devices, a time-delay relay device for effecting switching of said amplifier from one to the other of said pickup devices, band pass filter means directly connected in circuit with each of said pickup devices and having operating means whereby said relay device is energized in Iresponse to a fade signal from one of said pickup devices and is deenergized in response to a fade signal from the other of said pickup devices, thereby to transfer sound reproduction through said loudspeaker device from one to the other of said pickup devices.

CHESTER M. SINNETT. HERBERT BELAR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

